Scales are a device used for measuring how heavy something is. There are many different types of scales. Originally scales were made to balance like a seesaw, and you put the thing you wanted weighed on one side and weights on the other side until it balanced out.
Today, scales are often digital and need batteries to work. There are scales you stand on so you know how much you weigh, kitchen scales like in the picture so you can weigh food, and really big industrial scales to weigh trucks full of grain so it can be sold by weight.
A sifter is a device designed to get any lumps out of powders like flour for cooking, or to mix different powders together. A sifter is very similar to a sieve but it has a handle on the side that turns some blades inside the sifter around to make the process of sifting the powders faster and easier.
A stove is a hot surface for cooking on, usually found inside a kitchen, near an oven. Stoves have places to put pots and pans, with different sized heat sources for small and large pans.
Stoves can be heated by a wood fire, gas burners, or various types of elements powered by electricity.